1. Field of the Invention
The present invention relates to a heat exchanger, a spacer therefor and a partition therefor, which are used in a ventilation system with a heat exchanger wherein supplying fresh outdoor air and exhausting indoor air are simultaneously carried out to perform heat exchange between the supply air and the exhaust air, and in an air conditioning machine (total heat exchanging system for supply air and exhaust air) in an air conditioning machine room of e.g. a building.
2. Discussion of Background
Recent development in thermal insulation and airtightness for improving air conditioning and heating effects has given added importance to ventilation in a living space. It is effective to carry out heat exchange between supply air and exhaust air for ventilation without reducing the air conditioning and heating effects. In order to cope with such requirement, there have been known fixed ventilation systems with a heat exchanger which have been disclosed in e.g. JP-B-4719990 and JP-B-541054.
The conventional heat exchangers as mentioned above have such a structure that flat partitions 20 and corrugated spacers 21 are alternately layered as shown in a perspective view of FIG. 8, and that the respective spacers 21 are arranged to be perpendicular to their adjoined spacers in the layering process so as to provide a passage 22 for supply air and a passage 23 for exhaust air. In this Figure, an arrow indicated by A designates a supply airflow, and an arrow indicated by B designates an exhaust airflow. For example, when out door air in winter (fresh but cold air) passes through the passage 22 as the supply air, and when indoor heated air (contaminated but warm air) passes through the passage 23, as the exhaust air, the supply air and exhaust air carry out heat exchange through the partitions 20. The supplied air is heated by the heat exchange and is supplied indoors, and the exhaust air is cooled by the heat exchange and is exhausted outdoors.
In the case of total heat exchangers, the partitions 20 are made of e.g. converted paper dealt with a water-soluble polymer or a chemical agent (a material having a vapor permeability and a gas impermeability for e.g. air and carbon dioxide, (containing an absorbent, as disclosed in e.g. JP-A-542277. On the other hand, the spacers 21 are made of paper, giving importance to strength, workability and similarity to the partitions (expansion and contraction, and adhesion due to humidity). Use of these partitions and spacers can realize a high total heat exchange effectiveness.
In some of sensible heat exchangers, the partitions 20 and the spacers 21 have been made of a resin film. Such kind of sensible heat exchangers are constructed by joining a corrugated sheet to a noncorrugated sheet by fusion, cutting the joined sheets in a rectangular or parallelogram shape so as to provide several element units and layering the element units.
The demand for a ventilation system with a heat exchanger in cold districts or indoor warm swimming pools has increased with the spread of such kind of heat exchanges. Such environments have a problem in that a great temperature difference between supplied air and exhaust air is apt to form vapor condensation and that the above-mentioned converted paper can not withstand long use because of deformation due to the vapor condensation.
In order to solve this problem, there have been proposed a total heat exchanger wherein the partitions 20 are made of a moisture permeability and gas impermeability of element which is prepared from a polymer porous material having a good moisture resistance and coated with a water-soluble polymer including an absorbent, and the spacers 21 are made of polyethylene or polypropylene so as to have a corrugated shape (JP-B-425476), and a total heat exchanger wherein the partitions 20 are made of a porous material having a density with an air permeability of 20 sec/100 cc or more and coated with a water-insoluble and hydrophilic polymer (JP-B-48115).
These partitions 20 and spacers 21 have an advantage in that productibility is raised because the partitions and the spacers have a good bonding property with respect to each other, and that many structure units can be obtained by cutting a layered block. On the other hand, the spacers 21 have created a problem in that when air to be exhausted is at a high gas contamination level, the high gas permeability of the spacers allows the exhaust air to mix with supply air from end surfaces of the spacers as shown in FIG. 9, thereby contaminating the supply air by the exhaust air.
This problem has been solved by a heat exchanger wherein spacers are constituted by a gas impermeability film which is made of a porous material with a thin film having a gas impermeability in a structurally close contact therewith by overlapping, bonding or laminating, the spacers maintain spacing between adjoining partitions and two kinds of working airflows pass separated by the partitions (JP-A-7190666).
Total heat exchangers which have spacers provided with the gas impermeability film have solved the problem in that when air to be exhausted is at a high gas contamination level, exhaust air mixes with supply air to contaminate the supply air because the spacers 21 have a low gas permeability. Also, such total heat exchanger have offered the advantage in that productibility is raised because the partitions 20 and the spacers 21 have a good bonding property with respect to each other, and because many structure units can be obtained by cutting a layered block.
However, there has been created a problem in that material cost is increased and a time required for preparation is lengthened to raise cost because the spacers are constituted by a gas impermeability film which is made of a porous material with a thin film having a gas impermeability in a structurally close contact therewith by overlapping, bonding or laminating.
There has been created another problem in that it is difficult to form corrugation for maintaining spacing when heating and jointing by fusion are carried out in preparation of heat exchangers such as shaping or bonding because the porous material as a main material for the spacers has a softening temperature near to the softening temperature of the thin film.